U.S. patent number 5,923,926 [Application Number 08/939,482] was granted by the patent office on 1999-07-13 for developing device and electrophotographic image forming apparatus.
This patent grant is currently assigned to Canon Kabushiki Kaisha. Invention is credited to Nobuharu Hoshi, Hironobu Isobe.
United States Patent |
5,923,926 |
Isobe , et al. |
July 13, 1999 |
**Please see images for:
( Certificate of Correction ) ** |
Developing device and electrophotographic image forming
apparatus
Abstract
A developing cartridge for developing a latent image formed on
the photosensitive member, which is detachably mountable to a main
assembly of an electrophotographic image forming apparatus, the
developing cartridge includes a developing member for developing a
latent image formed on the photosensitive member; a toner
accommodating portion for accommodating toner to be used for
developing a latent image formed on the photosensitive member by
the developing member; a driving force receiving portion for
receiving, from the main assembly, driving force for rotating the
developing member when the developing cartridge is mounted to the
main assembly, the driving force receiving portion being provided
at a leading side of the developing cartridge when the developing
cartridge is mounted to the main assembly in a longitudinal
direction of the developing member; an exposed developing bias
contact, provided at the leading side, for receiving from the main
assembly a developing bias to be supplied to the developing member
when the developing cartridge is mounted to the main assembly;
wherein the driving force receiving portion is disposed inside the
developing bias contact in the longitudinal direction of the
developing member.
Inventors: |
Isobe; Hironobu (Numazu,
JP), Hoshi; Nobuharu (Numazu, JP) |
Assignee: |
Canon Kabushiki Kaisha (Tokyo,
JP)
|
Family
ID: |
26543869 |
Appl.
No.: |
08/939,482 |
Filed: |
September 29, 1997 |
Foreign Application Priority Data
|
|
|
|
|
Sep 30, 1996 [JP] |
|
|
8-258877 |
Sep 26, 1997 [JP] |
|
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9-261738 |
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Current U.S.
Class: |
399/119;
399/90 |
Current CPC
Class: |
G03G
15/0896 (20130101); G03G 2221/1648 (20130101); G03G
2215/0177 (20130101); G03G 2221/163 (20130101); G03G
2221/1815 (20130101); G03G 2215/0872 (20130101) |
Current International
Class: |
G03G
15/08 (20060101); G03G 015/00 (); G03G
015/06 () |
Field of
Search: |
;399/90,106,111,112,114,119,125,126 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Grimley; Arthur T.
Assistant Examiner: Chen; Sophia S.
Attorney, Agent or Firm: Fitzpatrick, Cella, Harper &
Scinto
Claims
What is claimed is:
1. A developing cartridge for developing a latent image formed on
an electrophotographic photosensitive member, which is detachably
mountable to a main assembly of an electrophotographic image
forming apparatus, said developing cartridge comprising:
a cartridge frame;
a developing member for developing a latent image formed on the
photosensitive member;
a toner accommodating portion for accommodating toner to be used
for developing a latent image formed on said photosensitive member
by said developing member;
a driving force receiving portion for receiving, from the main
assembly, a driving force for rotating said developing member when
said developing cartridge is mounted to the main assembly, said
driving force receiving portion being provided at a leading side of
said developing cartridge when said developing cartridge is mounted
to the main assembly in a longitudinal direction of said developing
member, wherein said driving force receiving portion is provided in
a recess in said cartridge frame;
a developing bias contact exposed outwardly through said cartridge
frame and provided at said leading side, for receiving from the
main assembly a developing bias to be supplied to said developing
member when said developing cartridge is mounted to the main
assembly;
wherein said driving force receiving portion is disposed inside
said developing bias contact in the longitudinal direction of the
developing member.
2. A developing cartridge according to claim 1, wherein a wall
constituting the recess is engaged with a positioning member
provided in the main assembly to correctly position said developing
cartridge when said developing cartridge is mounted to the main
assembly.
3. A developing cartridge according to claim 1 or 2, wherein said
driving force receiving portion is in the form of a circular member
having an axis at a position different from that of an axis of a
developing roller as said developing member, and by rotation of a
said driving force transmission member, said circular member is
rotated.
4. A developing cartridge according to claim 3, wherein the driving
force received by said circular member is transmitted to one end of
said developing roller through a gear disposed coaxial with said
developing roller.
5. A developing cartridge according to claim 3, wherein a free end
side of said driving force receiving portion is disposed inside a
surface of said developing bias contact by approx. 8.0 mm-18.0
mm.
6. A developing cartridge according to claim 1 or 2, further
comprising a toner remaining amount detecting contact exposed
through said cartridge frame and juxtaposed adjacent said
developing bias contact, for permitting the main assembly to detect
a remaining amount of toner in said toner accommodating
portion.
7. A developing cartridge according to claim 1, further comprising
a shutter movable between a covering position for covering a
surface of a developing roller as said developing member which
surface is otherwise exposed through said cartridge frame and an
exposing position, retracted from said covering position, for
exposing a surface of said developing roller, wherein a first
center of rotation of a first supporting arm for supporting one
longitudinal end of said shutter and a second center of rotation of
a second supporting arm for supporting one longitudinal end of said
shutter, are provided at a longitudinal end of said developing
member.
8. A developing cartridge according to claim 1, further comprising
a grip at one longitudinal end of said developing member, which is
usable when said developing cartridge is mounted to or unmounted
from the main assembly.
9. A developing cartridge according to claim 1 or 8, further
comprising a second grip, at the other longitudinal end of said
developing member, for pulling out a toner seal for unsealably
sealing a toner supply opening of said toner accommodating portion,
and wherein by pulling out the toner seal using said second grip
before start of use of said cartridge, said toner supply opening is
opened to permit the toner to be supplied to said developing member
from said toner accommodating portion.
10. A developing cartridge according to claim 1, wherein the main
assembly includes a swingable supporting member for supporting said
developing cartridge, said swingable supporting member being
swingable about an axis between a developing position for placing
said developing cartridge at an operating position for development
and a retracted position where said developing cartridge is
retracted from said operating position, and wherein said developing
cartridge is detachably mounted relative to said swingable
supporting member.
11. A developing cartridge for developing a latent image formed on
an electrophotographic photosensitive drum, which is detachably
mountable relative to a main assembly of an electrophotographic
image forming apparatus provided with a driving force transmission
member, said developing cartridge comprising:
a cartridge frame;
a developing roller for developing a latent image formed on the
photosensitive drum;
a toner accommodating portion for accommodating toner to be used
for developing the latent image formed on the photosensitive drum
by said developing roller;
a driving force receiving portion for receiving, from the main
assembly, a driving force for rotating said developing roller when
said developing cartridge is mounted to the main assembly, said
driving force receiving portion being provided at a leading side of
said developing cartridge when said developing cartridge is mounted
to the main assembly in a longitudinal direction of said developing
roller, wherein said driving force receiving portion is disposed in
a recess provided in said cartridge frame, and a wall constituting
a recess is engaged with a positioning member provided in the main
assembly when said developing cartridge is mounted to the main
assembly, wherein said driving force receiving portion is in the
form of a circular member having an axis at a position different
from that of an axis of said developing roller, and by rotation of
a driving force transmission member, said circular member is
rotated, and wherein the driving force received by said circular
member is transmitted to one end of said developing roller through
a gear disposed coaxial with said developing roller;
a developing bias contact exposed outwardly through said cartridge
frame and provided at said leading side, for receiving from the
main assembly a developing bias to be supplied to said developing
roller when said developing cartridge is mounted to the main
assembly;
a toner remaining amount detecting contact exposed outwardly
through said cartridge frame and juxtaposed adjacent said
developing bias contact, for permitting the main assembly to detect
a remaining amount of toner in said toner accommodating
portion;
wherein said driving force receiving portion is disposed inside
said developing bias contact in the longitudinal direction of the
developing roller.
12. A developing cartridge according to claim 11, wherein a free
end side of said driving force receiving portion is disposed inside
a surface of said developing bias contact by 8.0 mm-18.0 mm.
13. A developing cartridge according to claim 11, further
comprising a shutter movable between a covering position for
covering a surface of said developing roller which surface is
otherwise exposed through said cartridge frame and an exposing
position, retracted from said covering position, for exposing a
surface of said developing roller, wherein a first center of
rotation of a first supporting arm for supporting one longitudinal
end of said shutter and a second center of rotation of second
supporting arm for supporting one longitudinal end of said shutter,
are provided at a longitudinal end of said developing roller.
14. A developing cartridge according to claim 11, further
comprising a grip at one longitudinal end of said developing
roller, which is usable when said developing cartridge is mounted
to or unmounted from the main assembly.
15. A developing cartridge according to claim 14, further
comprising a second grip, at the other longitudinal end of said
developing roller, for pulling out a toner seal for unsealably
sealing a toner supply opening of said toner accommodating portion,
and wherein by pulling out the toner seal using said second grip
before start of use of said cartridge, said toner supply opening is
opened to permit the toner to be supplied to said developing roller
from said toner accommodating portion.
16. A developing cartridge according to claim 11, wherein the main
assembly includes a swingable supporting member for supporting said
developing cartridge, said swingable supporting member being
swingable about an axis between a developing position for placing
said developing cartridge at an operating position for development
and a retracted position retracted where said developing cartridge
is retracted from said operating position, and wherein said
developing cartridge is detachably mounted relative to said
swingable supporting member.
17. A developing cartridge for developing a latent image formed on
an electrophotographic photosensitive drum, which is detachably
mountable relative to a main assembly of an electrophotographic
image forming apparatus provided with a driving force transmission
member, said developing cartridge comprising:
a cartridge frame;
a developing roller for developing a latent image formed on the
photosensitive drum;
a toner accommodating portion for accommodating toner to be used
for developing the latent image formed on the photosensitive drum
by said developing roller;
a driving force receiving portion for receiving, from the main
assembly, a driving force for rotating said developing roller when
said developing cartridge is mounted to the main assembly, said
driving force receiving portion being provided at a leading side of
said developing cartridge when said developing cartridge is mounted
to the main assembly in a longitudinal direction of said developing
roller, wherein said driving force receiving portion is disposed in
a recess provided in said cartridge frame, and a wall constituting
said recess is engaged with a positioning member provided in the
main assembly when said developing cartridge is mounted to the main
assembly, wherein said driving force receiving portion is in the
form of a circular member having an axis at a position different
from that of an axis of a developing roller, and by rotation of a
driving force transmission member, said circular member is rotated,
and wherein the driving force received by said circular member is
transmitted to one end of said developing roller through a gear
disposed coaxial with said developing roller;
a developing bias contact exposed through said cartridge frame and
provided at said leading side, for receiving from the main assembly
a developing bias to be supplied to said developing roller when
said developing cartridge is mounted to the main assembly;
a toner remaining amount detecting contact exposed through said
cartridge frame and juxtaposed adjacent said developing bias
contact, for permitting the main assembly to detect a remaining
amount of toner in said toner accommodating portion;
a shutter movable between a covering position for covering a
surface of said developing roller, which surface is otherwise
exposed through said cartridge frame, and an exposing position,
retracted from said covering position, for exposing a surface of
said developing roller, wherein a first center of rotation of a
first supporting arm for supporting one longitudinal end of said
shutter and a second center of rotation of second supporting arm
for supporting one longitudinal end of said shutter, are provided
at one longitudinal end of said developing cartridge;
a grip at the other longitudinal end of said developing cartridge,
which is usable when said developing cartridge is mounted to or
demounted from the main assembly;
a second grip, at the other longitudinal end of said developing
cartridge, for pulling out a toner seal for unsealably sealing a
toner supply opening of said toner accommodating portion, and
wherein by pulling out the toner seal using said second grip before
start of use of said cartridge, said toner supply opening is opened
to permit the toner to be supplied to said developing roller from
said toner accommodating portion;
wherein a free end side of said driving force receiving portion is
disposed inside a surface of said developing bias contact by 8.0
mm-18.0 mm.
18. An electrophotographic image forming apparatus for forming an
image on a recording material, to which a developing cartridge is
detachably mountable, comprising:
a. a driving force transmission member for transmitting a driving
force;
b. a feeding member for feeding the recording material;
c. a mounting member for detachably mounting said developing
cartridge, which includes:
a cartridge frame;
a developing member for developing a latent image formed on a
photosensitive member;
a toner accommodating portion for accommodating toner to be used
for developing a latent image formed on said photosensitive member
by said developing member;
a driving force receiving portion for receiving, from the main
assembly, a driving force for rotating said developing member when
said developing cartridge is mounted to the main assembly, said
driving force receiving portion being provided at a leading side of
said developing cartridge when said developing cartridge is mounted
to the main assembly in a longitudinal direction of said developing
member, wherein said driving force receiving portion is provided in
a recess formed in said cartridge frame;
a developing bias contact exposed outwardly through said cartridge
frame and provided at said leading side, for receiving from the
main assembly a developing bias to be supplied to said developing
cartridge is mounted to the main assembly;
wherein said driving force receiving portion is disposed inside
said developing bias contact in the longitudinal direction of the
developing member.
19. An electrophotographic image forming apparatus for forming an
image on a recording material, to which a developing cartridge is
detachably mountable, comprising:
a. a driving force transmission member for transmitting driving
force;
b. a feeding member for feeding the recording material;
c. a mounting member for detachably mounting a developing
cartridge;
said developing cartridge including:
a cartridge frame;
a developing roller for developing a latent image formed on a
photosensitive drum;
a toner accommodating portion for accommodating toner to be used
for developing the latent image formed on the photosensitive drum
by asid developing roller;
a driving force receiving portion for receiving, from the main
assembly, a driving force for rotating said developing roller when
said developing cartridge is mounted to the main assembly, said
driving force receiving portion being provided at a leading side of
said developing cartridge when said developing cartridge is mounted
to the main assembly in a longitudinal direction of said developing
roller, wherein said driving force receiving portion is disposed in
a recess provided in said cartridge frame, and a wall constituting
a recess is engaged with a positioning member provided in the main
assembly when said developing cartridge is mounted to the main
assembly, wherein said driving force receiving portion is in the
form of a circular member having an axis at a position different
from that of an axis of said developing roller, and by rotation of
said driving force transmission member, said circular member is
rotated, and wherein the driving force received by said circular
member is transmitted to one end of said developing roller through
a gear disposed coaxial with said developing roller;
a developing bias contact exposed outwardly through said cartridge
frame and provided at said leading side, for receiving from the
main assembly a developing bias to be supplied to said developing
roller when said developing cartridge is mounted to the main
assembly;
a toner remaining amount detecting contact exposed outwardly
through asid cartridge frame and juxtaposed adjacent said
developing bias contact, for permitting the main assembly to
detects a remaining amount of toner in said toner accommodating
portion;
wherein said driving force receiving portion is disposed inside
said developing bias contact in the longitudinal direction of the
developing roller.
20. An electrophotographic image forming apparatus for forming an
image on a recording material, to which a developing cartridge is
detachably mountable, comprising:
a. a driving force transmission member for transmitting driving
force;
b. a feeding member for feeding the recording material;
c. a mounting member for detachably mounting a developing
cartridge;
said developing cartridge including:
a cartridge frame;
a developing roller for developing a latent image formed on a
photosensitive drum;
a toner accommodating portion for accommodating toner to be used
for developing the latent image formed on the photosensitive drum
by said developing roller;
a driving force receiving portion for receiving, from the main
assembly, a driving force for rotating said developing roller when
said developing cartridge is mounted to the main assembly, said
driving force receiving portion being provided at a leading side of
said developing cartridge when said developing cartridge is mounted
to the main assembly in a longitudinal direction of said developing
roller, wherein said driving force receiving portion is disposed in
a recess provided in said cartridge frame, and a wall constituting
a recess is engaged with a positioning member provided in the main
assembly when said developing cartridge is mounted to the main
assembly, wherein said driving force receiving portion is in the
form of a circular member having an axis at a position different
from that of an axis of a developing roller, and by rotation of
said driving force transmission member, said circular member is
rotated, and wherein the driving force received by said circular
member is transmitted to one end of said developing roller through
a gear disposed coaxial with said developing roller;
a developing bias contact exposed outwardly through said cartridge
frame and provided at said leading side, for receiving from the
main assembly a developing bias to be supplied to said developing
roller when said developing cartridge is mounted to the main
assembly;
a toner remaining amount detecting contact exposed outwardly
through asid cartridge frame and juxtaposed adjacent said
developing bias contact, for permitting the main assembly to
detects a remaining amount of toner in said toner accommodating
portion;
a shutter movable between a covering position for covering a
surface of said developing roller, which surface is otherwise
exposed through said cartridge frame, and an exposing position,
retracted from said covering position, for exposing a surface of
said developing roller, wherein a first center of rotation of a
first supporting arm for supporting one longitudinal end of said
shutter and a second center of rotation of a second supporting arm
for supporting said one longitudinal end of said shutter, are
provided at one longitudinal end of said developing cartridge;
a grip at the other longitudinal end of said developing cartridge,
which is usable when said developing cartridge is mounted to or
unmounted from the main assembly;
a second grip, at the other longitudinal end of said developing
cartridge, for pulling out a toner seal for unsealably sealing a
toner supply opening of said toner accommodating portion, and
wherein by pulling out the toner seal using said second grip before
start of use of said cartridge, said toner supply opening is opened
to permit the toner to be supplied to said developing roller from
said toner accommodating portion;
wherein a free end side of said driving force receiving portion is
disposed inside a surface of said developing bias contact by 8.0
mm-18.0 mm.
Description
FIELD OF THE INVENTION AND RELATED ART
The present invention relates to a developing device usable with an
electrophotographic image forming apparatus such as an
electrophotographic copying machine, printer or the like, and an
electrophotographic image forming apparatus using the same.
The electrophotographic image forming apparatus means an apparatus
which forms an image on a recording material using an
electrophotographic image forming process. It includes for example
an electrophotographic copying machine, an electrophotographic
printer (LED printer, laser beam printer), an electrophotographic
printer type facsimile machine and an electrophotographic printer
type word processor.
Recently, demand for color electrophotographic image forming
apparatus capable of forming color images, is increasing.
On the other hand, in a color electrophotographic image forming
apparatus compatible with future network, high speed and high
volume monochromatic image printing is desired as well as the color
printing.
In a known color developing device, all of four color developing
devices 105M, 105C 105Y, 105K are carried on a turret (for example,
U.S. Pat. No. 4,707,108, or U.S. Pat. No. 5,040,031). Such a
structure is very effective in color image formation. The present
invention is directed to a further development.
SUMMARY OF THE INVENTION
Accordingly, it is a principal object of the present invention to
provide a developing cartridge and an electrophotographic image
forming apparatus wherein driving force can be assuredly
transmitted from a main assembly of an electrophotographic image
forming apparatus to the developing cartridge. It is another object
of the present invention to provide a developing cartridge and an
electrophotographic image forming apparatus wherein when the
developing cartridge is mounted to a main assembly of the
electrophotographic image forming apparatus, driving force can be
transmitted from a driving force at the positioning portion
relative to the main assembly.
It is a further object of the present invention to provide a
developing cartridge and an electrophotographic image forming
apparatus wherein transmission of driving force from a main
assembly of an electrophotographic image forming apparatus to a
developing cartridge is effected by a coupling so that rotation
non-uniformity of the developing member can be reduced.
According to an aspect of the present invention, there is provided
a developing cartridge for developing a latent image formed on the
photosensitive member, which is detachably mountable to a main
assembly of an electrophotographic image forming apparatus, the
developing cartridge comprising: a developing member for developing
a latent image formed on the photosensitive member; a toner
accommodating portion for accommodating toner to be used for
developing a latent image formed on the photosensitive member by
the developing member; a driving force receiving portion for
receiving, from the main assembly, driving force for rotating the
developing member when the developing cartridge is mounted to the
main assembly, the driving force receiving portion being provided
at a leading side of the developing cartridge when the developing
cartridge is mounted to the main assembly in a longitudinal
direction of the developing member; an exposed developing bias
contact, provided at the leading side, for receiving from the main
assembly a developing bias to be supplied to the developing member
when the developing cartridge is mounted to the main assembly;
wherein the driving force receiving portion is disposed inside the
developing bias contact in the longitudinal direction of the
developing member.
These and other objects, features and advantages of the present
invention will become more apparent upon a consideration of the
following description of the preferred embodiments of the present
invention taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an illustration of an entirety of a color laser printer
according to an embodiment of the present invention.
FIG. 2 shows an outer appearance of a color laser printer.
FIG. 3 is a perspective view of a black developing device before it
is mounted to a swingable guide portion.
FIG. 4 is a perspective view of a swingable guide portion.
FIG. 5 is a perspective view of a toner accommodating portion of a
black developing device.
FIG. 6 is a perspective view of an outer appearance of a black
developing device.
FIG. 7 is a side view of a rear side of a black developing
device.
FIG. 8 is a perspective view of a front side of a black developing
device.
FIG. 9 is a sectional view of a drive transmission structure to a
black developing device.
FIG. 10 is an illustration which a state in which black developing
device and a swingable guide portion are engaged with each
other.
FIG. 11 is a cross-sectional view of a black developing device
which is mounted.
FIG. 12 is a perspective view of a black developing device which is
mounted to a swingable guide portion and which is contacted to a
photosensitive drum.
FIG. 13 is a side view of a front side, in the mounted state, of a
black developing device.
FIG. 14 is an enlarged view of a rear side of a black developing
device when it is mounted.
FIG. 15 is an enlarged view of a rear side of a black developing
device when it is mounted.
FIG. 16 is a front view of a black developing device as seen from a
downstream side in a direction along which it is mounted to the
main assembly (it is mounted to the main assembly).
FIG. 17 is a rear view of a black developing device as seen from a
downstream side in a direction along which it is mounted to the
main assembly (it is mounted to the main assembly).
FIG. 18 is a side view of a black developing device which is at a
developing position of the main assembly of the apparatus.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to the accompanying drawings, the embodiments of the
present invention will be described. First, the description will be
made as to a structure of a color electrophotographic image forming
apparatus, and then as to a structure of a black developing device
used therewith.
(General arrangement of color electrophotographic image forming
apparatus)
FIG. 1 shows a general arrangement of a color laser printer as a
color electrophotographic image forming apparatus according to an
embodiment of the present invention, and FIG. 2 is an outer
appearance thereof.
The color laser printer P of this embodiment comprises an
electrophotographic photosensitive member in the form of a drum
(photosensitive drum) 15 which rotates at a constant speed, a
developing device 21B (for development with black color toner),
three color development devices (yellow developing device 20Y for
development with yellow color toner, magenta developing device 20M
for development with magenta color toner, and a cyan developing
device 20C for development with cyan color toner) detachably
mountable to a rotatable or revolvable turret.
Below the photosensitive drum 15, there is provided an intermediary
transfer member 9 for carrying a superposedly transferred color
image and for transferring the image onto a recording material 2
fed from a feeding portion.
The recording material 2 onto which the color image has been
transferred, is fed to a fixing portion 25 to fix the color image
on the recording material 2, and then the recording material 2 is
discharged to a discharging portion 37 at the top of the apparatus
by discharging rollers 34, 35, 36.
The rotatable or revolvable color development devices and the fixed
black developing device are detachably mountable relative to the
main assembly of the printer, independently from each other.
The description will be made as to various parts of the image
forming apparatus P.
(Drum unit)
A drum unit 13 integrally contains the photosensitive drum 15 and a
container 14 of a cleaning device functioning as a holder for the
drum 15. The drum unit 13 is detachably mountable relative to the
main assembly of the printer, and can be easily exchangeable when
the lifetime of the photosensitive drum 15 is reached.
The photosensitive drum 15 of this embodiment comprises an aluminum
cylinder having a diameter of 62 mm approx. and an organic
photoconductive layer applied to the outside of the aluminum
cylinder, and is rotatably supported on the container 14 of the
cleaning device which functions also as a housing for the
photosensitive drum 15.
A cleaner blade 16 and a primary charging means 17 are contacted to
the outer peripheral surface of the photosensitive drum 15. The
photosensitive drum 15 receives driving force transmitted from a
driving motor (unshown) at one longitudinal end, and is rotated in
the counterclockwise direction in accordance with an image forming
operation.
(Charging means)
The charging means 17 is a contact charging type charger. An
electroconductive roller is contacted to a photosensitive drum 15,
and the surface of the photosensitive drum 15 is uniformly charged
by application of a voltage to the electroconductive roller.
(Exposing means)
The exposure of the photosensitive drum 15 is effected by a scanner
30. More particularly, an image signal is supplied to a laser
diode, and the laser diode projects a beam onto a polygonal mirror
31 at a timing corresponding the image signal. The polygonal mirror
31 rotates at a high speed by a scanner motor; the beam reflected
by the polygonal mirror 31 is selectively projected onto the
surface of the photosensitive drum 15 through an imaging lens 32
and a reflection mirror 33, so that charge latent image is formed
on the photosensitive drum 15.
(Developing means)
The developing means includes three rotary developing devices 20Y,
20M, 20C for development in yellow, magenta and cyan colors, and
one black developing device 21B for development in black color to
visualize the electrostatic latent image.
The black developing device 21B is a fixed developing device at a
developing position for effecting the developing operation, except
upon the mounting and demounting thereof relative to the main
assembly of the apparatus. A developing roller 21BS is disposed
opposed to the photosensitive drum 15 with a small clearance
(approx. 300 .mu.m) therebetween. It develops an image to visualize
a black image with black toner on the photosensitive drum 15.
The black developing device 21B, as shown in FIG. 1, feeds the
toner from the toner accommodating container toward the developing
roller 21BS by a feeding mechanism 21BA. The toner application
blade 21BB press-contacted to the outer periphery of the developing
roller 21BS applies the toner in the form of a thin layer on the
outer periphery of the developing roller 21BS which is rotating in
the indicated clockwise direction, and applies the charge to the
toner (triboelectric charge). The developing roller 21BS is
supplied with a developing bias, so that reverse development
(jumping development) corresponding to the electrostatic latent
image on the photosensitive drum 15 is effected to form a toner
image on the surface of the drum.
In this embodiment, the toner capacity of the black developing
device 21B is enough to print 15000 pages (A4, 5% print) which is
larger than twice that of the toner capacity of Y, M, C developing
devices, in consideration of the toner consumption corresponding to
the nature of the documents or image patterns printed by users.
By this, the frequency of exchange of the black developing device
by the users can be reduced.
The position of the black developing device 21B is, as shown in
FIG. 1, is between the projection position where the photosensitive
drum 15 is exposed to the beam from the laser scanner and a
development position where the photosensitive drum 15 is subjected
to a developing operation by the Y, M, C developing devices. Thus,
the laser scanner is disposed above the developing devices. By the
positional relation, the toner which might leak when the Y, M, C
developing devices are revolved, is prevented from scattering to
the optical parts such as a laser scanner. Therefore, the polygonal
mirror, the lens, the mirror and the like are protected from toner
deposition, so that sharp output images can be provided.
On the other hand, the three revolvable developing devices 20Y,
20M, 20C each contain the toner for 6000 pages (A4, 5% printing).
The three revolvable developing devices are detachably mounted on a
developing turret 23 which is revolvable about a shaft 22.
Upon the image formation, the turret 23 revolves about the shaft 22
while holding the Y, M, C developing devices to place a
predetermined developing device to be faced to the photosensitive
drum 15. The developing roller 20YS of the developing device placed
at the development position is disposed opposed to the
photosensitive drum 15 with a small clearance (300 .mu.m approx.),
and develops the electrostatic latent image on the photosensitive
drum 15 into a visualized image.
Upon the color image formation, the developing turret 23 rotates
for one rotation of the intermediary transfer member 9 so that
developing processes are carried out in the order of yellow
developing device 20Y, magenta developing device 20M, cyan
developing device 20C and the black developing device 21B.
For example, when the yellow revolvable developing device 20Y is
positioned at the developing position faced to the photosensitive
drum unit, the yellow revolvable developing device 20Y feeds the
toner from the container to the application roller 20YR by a
feeding mechanism. By the functions of the application roller 20YR
rotating in the clockwise direction and the blade 20YB
press-contacted to the outer periphery of the developing roller
20YS, a thin layer of the toner is applied on the outer periphery
of the developing roller 20YS rotating in the clockwise direction
in FIG. 1, and the toner is triboelectrically charged. The
developing roller 20YS is supplied with a developing bias so that
latent image formed on upper is developed. The development is
effected through the same process as to the magenta developing
device 20M and the cyan developing device 20C. The application of
the bias to each developing roller and the transmission of the
driving force thereto is carried out when the developing device is
placed at the developing position.
(Intermediary transfer member)
The intermediary transfer member 9 superimposedly receives four
visualized toner images (Y, M, C, B) from the photosensitive drum
15. It is rotated in the clockwise direction as shown in FIG. 1 in
synchronism with the outer peripheral speed of the photosensitive
drum 15.
The superimposed toner images on the intermediary transfer member 9
are transferred all together by a transfer roller 10 supplied with
a voltage, onto a recording material 2 fed to and nipped between
the intermediary transfer member 9 and the transfer roller 10.
The intermediary transfer member 9 in this embodiment, comprises an
aluminum cylinder 12 having a diameter of 186 mm and an elastic
layer 11 such as intermediate resistance sponge, intermediate
resistance rubber or the like on the outer periphery of the
aluminum cylinder 12. The intermediary transfer member 9 is
rotatably supported and is driven by a gear (unshown) fixed
thereto.
(Cleaning means)
The cleaning means functions to remove the toner on the
photosensitive drum 15 after the toner image provided by the
developing means on the photosensitive drum 15 is transferred onto
the intermediary transfer member 9. Thereafter, the removed toner
is accumulation in the cleaner container 14. Normally, the amount
of the removed toner accumulated in the container 14 does not fill
the container 14 before the lifetime of the photosensitive drum is
reached. Accordingly, normally the cleaner container 14 is
exchanged integrally and simultaneously with the lifetime-end
exchange of the photosensitive drum 15.
(Feeding portion)
The feeding portion functions to feed the recording material 2 into
the image formation station. It comprises a cassette 1 for
accommodating a plurality of recording materials 2, a pick-up
roller 3, a feeding roller 4, a retarding roller 5 for preventing
double feeding, a feeding guide 6 and a registration roller 8.
Upon image formation, the feeding roller 3 is rotated in accordance
with the image forming operation to feed the recording materials 2
from the cassette 1 one by one. The recording material 2 separated
and fed out, is guided by a guide 6, and introduced to the
registration roller 8 by the feeding roller 7. During the image
forming operation, the registration roller 8 rotates and stops at a
predetermined sequence to feed the recording material 2 in
synchronism with the transfer process.
(Transfer portion)
The transfer portion is provided with a swingable transfer roller
10. The transfer roller 10 comprises a metal shaft wrapped with an
intermediate resistance foamed elastic member and a driving shaft,
and is movable in the vertical direction in FIG. 1.
While the four color toner images are formed on the intermediary
transfer member 9, that is, while the intermediary transfer member
9 is rotated a plurality of turns, the transfer roller 10 is at a
lower position as shown in FIG. 1, and is separated from an
intermediary transfer member 9 so that toner image is not
disturbed.
After the four color toner images are formed on the intermediary
transfer member 9, the transfer roller 10 is urged toward an upper
position indicated by chain lines in FIG. 1 at a predetermined
pressure toward the intermediary transfer member 9 at predetermined
timing for transferring the color image onto the recording material
2. Simultaneously therewith, the transfer roller 10 is supplied
with a bias voltage so as to transfer the toner image onto the
recording material 2 from the intermediary transfer member 9.
The recording material 2 nipped between the intermediary transfer
member 9 and the transfer roller 10, is advanced at a predetermined
speed to the left in FIG. 1 during the transfer process, and is fed
to a fixing device.
(Fixing portion)
The fixing station 25 functions to fix the toner image on the
recording material. As shown in FIG. 1, the fixing portion 25
comprises a fixing roller 26 for applying heat to the recording
material 2, a pressing roller 27 for press-contacting the recording
material 2 to the fixing roller 26. These rollers are hollow and
contain heaters 28, 29. By the rotation of the rollers, the
recording material 2 is fed. The recording material 2 carrying the
toner image is fed by the fixing roller 26 and the pressing roller
27, and simultaneously therewith, the heat and pressure are applied
by which the toner image is fixed on the recording material 2.
(Black developing device)
Referring to FIGS. 3 to 18, the mounting of the black developing
device to the main assembly and the positioning method therefor
will be described, the black developing device being mountable and
demountable relative to the main assembly separately from the
above-described color developing devices.
FIG. 3 is a perspective view of a black developing device 21B
before it is mounted to a swingable guide portion 50. FIG. 4 is a
perspective view of a swingable guide portion. FIG. 5 is a
perspective view of a toner accommodating portion 21BK of a black
developing device 21. FIG. 6 is a perspective view of an outer
appearance of a black developing device 21B. FIG. 7 is a side view
of a rear side of the black developing device 21B. FIG. 8 is a
perspective view of a front side of a black developing device 21B.
FIG. 9 is a sectional view of a drive transmission structure to a
black developing device 21B. FIG. 10 is an illustration which a
state in which black developing device 21B and a swingable guide
portion 50 are engaged with each other. FIG. 11 is a sectional view
when the black developing device is mounted. FIG. 12 is a
perspective view of a black developing device 21B which is mounted
to a swingable guide portion 50 and which is contacted to a
photosensitive drum 15. FIG. 13 is a side view of a front side when
the black developing device is mounted. FIG. 14 and FIG. 15 are
enlarged views of the rear side when the black developing device is
mounted to the main assembly of the apparatus. FIG. 16 is a side
view of a leading side (with respect to the direction of mounting
of the developing device to the main assembly) when the black
developing device 21B is mounted to the main assembly, and FIG. 17
is a side view of a trailing side thereof, and FIG. 18 is a side
view when the black developing device is at the developing position
of the main assembly. In following description, the side of the
main assembly which is at the leading side in the black developing
device 21B inserting direction is called "rear side", and the side
of the main assembly at the trailing side is called "front
side".
The black developing device 21B comprises a housing and a
developing roller 21BS rotatably mounted thereto, said housing
comprising a first housing 21BE including a toner accommodating
portion, a holders 21BF, 21BR which are a second housing, at the
longitudinal opposite sides thereof. The housing is provided with
an openable shutter 21BO for protecting the developing roller 21BS,
and the black developing device 21B is detachably mountable
relative to the swingable guide portion 50 of the main assembly 80
of the apparatus.
(Mounting of the black developing device)
The swingable guide portion 50 has a swingable side plate 50B fixed
to the rear side of the swingable guide 50A. The swingable guide
50A has a swing hole 50M at the front side, and the rear side
swingable side plate 50B has a swing hole 50N.
The front side plate 60 of the main assembly 80 has a first swing
shaft 54 fixed thereto, and the rear side plate 61 has a second
swing shaft 55 fixed thereto. The first swing shaft 54 and the
second swing shaft 55 are engaged with the swing hole 50M and the
swing hole 50N, respectively.
The swingable guide portion 50 is swingable about the swing shafts
54, 55 by the engagement between the swing shaft 54, 55 and the
holes 50M, 50N. An axis connecting the first swing shaft 54 and the
second swing shaft 55 is parallel with a generating line of the
photosensitive drum 15, and the swingable guide portion 50 is
swingable in a direction perpendicular to the generating line of
the photosensitive drum 15. Thus, the developing roller 21BS of the
black developing device 21B mounted to the swingable guide portion
50 becomes parallel with the photosensitive drum 15.
The swingable guide portion 50 is swung by a rotation lever 51. The
rotation lever 51 is disposed at the front side 80a (FIG. 2) of the
main assembly 80. A cam 52 is fixed coaxially to a rotation lever
shaft 53 of the rotation lever 51, and rotates in the same phase as
the rotation of the rotation lever 51. When the rotation lever 51
is rotated, the cam 52 rotates, and the outer surface of the cam 52
slides on the swingable guide 50A and the swingable side plate 50B.
By the sliding operation, the swingable guide portion 50 swings
vertically about the swing shafts 54, 55.
In this embodiment, the rotation lever 51 is rotatable from a
horizontal position to a vertical position through approx.
90.degree., by which the swingable guide portion 50 swings about
10.degree..
When the black developing device 21B is inserted into the main
assembly 80, the rotation lever 51 is rotated to the horizontal
position. At this time, as shown in FIG. 3, an insertion opening 63
formed in a front side 80a of the main assembly 80 is completely
opened. When a fresh black developing device 21B is used, the user
shakes the black developing device 21B sufficiently, and then, a
toner seal 21BT (FIG. 11) is pulled out, and loads the black
developing device 21B into the main assembly 80. The shaking is to
loosen or uncake the toner in the toner accommodating portion
21BK.
If, however, the user shakes the black developing device 21B in its
longitudinal direction, or if, after the shaking, the user holds it
vertically, a larger amount of the uncaked toner may be at one
side. However, in this embodiment, as shown in FIG. 5, there are
provided a plurality of partitions 21BN adjacent the opening 21BM
of the toner accommodating portion 21BK, and therefore, the problem
can be avoided.
After the preparation for the mounting of the black developing
device 21B is completed, the user holds the black developing device
21B horizontally, and inserts it into the insertion opening 63. As
shown in FIG. 6, the holder 21BR at the black developing device 21B
side is provided with a guide rib 21BC which is roughly aligned
with the entrance of the swingable guide 50A. There is a nominal
play of 0.5-2 mm between the guide rib 21BC and the entrance of the
swingable guide 50A. Therefore, the user roughly aligns the black
developing device 21B with the entrance of the swingable guide 50A,
and then, pushes it toward rear side, thus smoothly loading it.
The black developing device 21B is provided with a shutter 21BO for
protecting the developing roller 21BS, the shutter 21BO being
rotation. To the holder 21BR disposed at a rear side of the black
developing device 21B, a shutter openable member 21BP is positioned
for rotation about the 21BP1, and is pushed in one direction by a
spring (unshown). The shutter shaft 21BQ is extended bridging
beyond the holder 21BF disposed at the front side 80a, and is
supported rotatably on a shaft 21BQ1 coaxial with the developing
roller 21BS.
One supporting portion 21B1 of the shutter 21BO is supported on a
shutter opening member 21BP, and the other supporting portion 21B2
is supported by the shutter shaft 21BQ. More particularly, the
shutter 21BO is supported at two positions in a cross-sectional
plane by the shutter opening member 21BP and the shutter shaft
21BQ. With this state, when the other end portion 21BP1 of the
shutter opening member 21BP receives a rotation moment in a
direction perpendicular to the generating line of the
photosensitive member 15, the shutter opening member 21BP rotates
about the shaft 21BP2, so that shutter 21BO rotates smoothly. The
FIG. 7 shows the shutter 21BO when it is at the closing
position.
In this embodiment, as shown in FIGS. 7 and 11, there is provided a
stopper 21BZ in the form of a projection in the rotation region of
the shutter shaft 21BQ, so that movement of the shutter 21BO in the
opening direction is stopped by abutment of the shutter shaft 21BQ
to the stopper 21BZ.
In this embodiment, the end of the rotation center shaft 21BQ1 of
the shutter shaft 21BQ is inserted in holes 21BL (only front side
is shown) formed in the front side holder 21BF and the rear side
holder 21BR. As shown in FIG. 6, the holder 21BF at the front side
is provided with a hole 21BL in the form of a cut-away portion into
which an end of the shutter shaft 21BQ can be press-fitted in a
radial direction. With this structure, the assembling can be
carried out easily by press-fitting the shutter shaft 21BQ into the
hole 21BL.
As shown in FIG. 8, the end of the shutter shaft 21BQ may be
mounted to the side surface of the holder 21BF, using a shutter
bearing 21BT. In such a case, the mounting can be carried out in
the same direction as the generating line of the photosensitive
drum 15, and then, the mounting is further easier.
To make the shutter opening member 21BP rotatable, the swingable
guide portion 50 is provided with a guiding member 50J as shown in
FIGS. 3 and 4 in this embodiment. The guiding member 50J is fixed
to the swingable guide 50A, and has a wall surface in the form of a
non-acute inclined surface. When the user inserts the black
developing device 21B into the swingable guiding member 50 to a
certain extent, the other end portion 21BP1 of the shutter opening
member 21BP is abutted to the guiding member 50J. With further
insertion of the black developing device 21B, the other end portion
21BP3 of the shutter opening member 21BP is moved along the
inclined surface formed in the guiding member 50J. When the motion
of the shutter opening member 21BP is seen in the cross-section,
the shutter opening member 21BP is rotating about 21BP2. With such
a structure, the shutter 21BO is opened and closed in interrelation
with the inserting operation of the black developing device
21B.
In order to rotate the shutter opening member 21BP smoothly, the
angle of the inclined surface portion of the guiding member 50J is
desirably not more than 45.degree., and in this embodiment it is
approx. 15.degree.. When the length of the black developing device
21B is short (for A4 size), the opening and closing operation has
to be carried out through a short stroke, and therefore, the
inclined surface portion of the guiding member 50J is larger than
15.degree. and not more than 45.degree..
(Positioning and drive transmission at the rear side of the black
developing device)
The side surface of the holder 21BR at the rear side of the black
developing device 21B is provided with a drive input engaging
portion 21BV and a second positioning hole 21BD functioning as the
positioning portion for positioning it relative to the swingable
guide portion 50. On the other hand, the swingable side plate 50B
of the swingable guide portion 50 is provided with a drive
transmission engaging portion 50L and a second positioning shaft
50K.
As shown in FIG. 9, when the black developing device 21B is
inserted into the swingable guide portion 50A, the drive
transmitting portion provided in the swingable guide portion 50A
and the driving force input portion of the black developing device
21B are coupled.
The driving force transmitting portion 50P comprises a drive
transmitting shaft 50E for transmitting the driving force to the
driving force input portion 50Q of the black developing device 21B,
a drive transmission gear 50F (FIG. 4) for transmitting the
rotation force to the drive transmitting shaft 50E, and a drive
transmission engaging portion 50L engageable with the driving input
engaging portion 21BV provided in the driving force input portion
50Q of the black developing device 21B. The driving force input
portion 50Q has a driving input gear 21BG for drive transmission of
the driving force received by the engaging portion 21BV to the
developing roller 21BS.
Referring to FIGS. 4 and 9, the structure of the driving force
transmitting portion 50P and the driving force input portion 50Q
will be described. A side surface of the transmission shaft 50E is
supported by the housing 50C and the housing 50D. The drive
transmitting shaft 50E has a drive transmission gear 50F fixed
thereto, and is urged in one direction by a driving shaft confining
spring 50G. Drive transmission engaging portion 50L is coaxially
and integrally with the drive transmitting shaft 50E. Therefore,
the drive transmitting shaft 50E is rotatable coaxially with the
drive transmission engaging portion 50L.
As shown in FIG. 4, the engaging portion 50L is circular. When the
black developing device 21B is mounted to the main assembly 80 of
the apparatus, the circular portion of the engaging portion 50L is
engaged with the circular engaging portion 21BV of the developing
device 21B. By this, the developing device 21B is positioned
relative to the main assembly 80 at the rear side.
On the other hand, the female coupling recess 21BG in the black
developing device 21B is supported by developing roller driving
bearings 21BI, 21BJ at the opposite ends. The developing roller
driving bearing 21BI is supported by the driving input engaging
portion 21BV formation in the holder 21BR. The center of rotation
of the female coupling recess 21BG is coaxial with the drive
transmission engaging portion 50L. Thus, the developing roller
driving gear 21BG is rotated coaxially with the drive transmission
engaging portion 50L. The female coupling recess 21BG is provided
inside the outer surface of the holder 21BI. This is because the
circular portion of the drive transmission engaging portion 50L is
engaged therewith.
With this structure, when the drive transmission engaging portion
50L is inserted into the driving input engaging portion 21BV, the
drive transmitting shaft 50E is rotated coaxially with the
developing roller driving gear 21BG. The developing roller driving
gear 21BG drives the developing roller gear 21BH (FIG. 6) to rotate
the developing roller 21BS. In this embodiment, the drive
transmission for the black developing device 21B is effected by the
coupling engagement, the rotation non-uniformity of the developing
roller 21BS can be reduced.
In this embodiment, one end of the drive transmitting shaft 50E has
an I-configuration 50EI (FIG. 4) having two cut surfaces. On the
other hand, an end of the developing roller driving gear 21BG has
two walls 21BG1 at symmetrical positions (FIG. 7). When the black
developing device 21B is inserted, the shaft end surface 50EL of
the I-configuration is inserted between the walls 21BG1 of the
developing roller driving gear 21BG to transmission the driving
force.
When the shaft end surface 50EL of drive transmitting shaft 50E is
not aligned in phase with the wall 21BI of the developing roller
driving gear 21BG upon the insertion of the black developing device
21B, the shaft end surface 50EL of the drive transmitting shaft 50E
interferes the end 21BG1 of the developing roller driving gear
21BG, and therefore, the driving force transmission is not
accomplished. However, in this embodiment, the drive transmitting
shaft 50E is press-contacted in one direction by the confining
spring 50G, and therefore, when the drive transmitting shaft 50E
rotates a certain extent, the shaft end surface 50EL is engaged
between the walls 21BG1 of the driving gear 21BG, so that driving
force transmission is enabled.
When the user pushes the black developing device 21B into the rear
side of the swingable guide portion 50, the driving input engaging
portion 21BV and the second positioning hole 21BD are brought into
engagement with the drive transmission engaging portion 50L and the
second positioning shaft 50K. By the two positioning portions, the
rear side of the black developing device 21B is correctly
positioned relative to the swingable guide portion 50, and the
position thereof is determined in the direction perpendicular to
the generating line of the photosensitive drum.
In this embodiment, before the positioning is finally determined,
the opening action of the shutter 21BO is completed.
At the rear side of the swingable guide 50A, a regulating member
50I for the black developing device is disposed. The regulating
member 50I is engaged with an engaging portion 21BW (FIG. 7) formed
at the rear side of the black developing device 21B. By this
engagement, the black developing device 21B is confined in the
position thereof in the direction of the generating line of the
photosensitive drum.
As shown in FIG. 10, when the user is pushed the black developing
device 21B to the rear, the black development regulating member 50I
having a resiliency enters the engaging portion 21BW, so that user
feels that black developing device 21B is set at the regular
position. The regulating member 50I prevents the black developing
device 21B from offsetting toward the user, when the rotation lever
51 is rotated to swing the black developing device 21B and the
swingable guide portion 50.
With this state, when the user rotates the lever 51 to rotate the
swingable guide portion 50A into a set position, the drive
transmission gear 50F fixed to the drive transmitting shaft 50E is
brought into engagement with the black developing device driving
gear 57 which is provided in the driving unit 56 of the main
assembly 80 and which is connected with the driving source
(unshown). By this, the drive transmission gear 50F is connected
with the driving source to permit rotation of the developing roller
21BS.
The driving unit 56, as shown in FIGS. 14 and 15, is provided with
a color developing device driving gear 58 connected with the
driving source (unshown) and a drum driving gear 59 to transmit the
driving force to the developing devices 21M, 21C, 21Y and to the
photosensitive drum 15.
(Positioning of the black developing device at the front side)
A front side holder 21BF for the black developing device 21B is
provided with an elongated hole 21BY functioning as a pivot of the
swing of the black developing device 21B, as shown in FIGS. 7 and
8. When the black developing device 21B is inserted into the
swingable guide portion 50, the elongated hole 21BY functions an
engaging portion for engagement with the swing shaft 54 arranged on
the side plate 60 at the front side 80a of the main assembly
80.
Depending on the part accuracy of the black developing device and
the main assembly 80, it is not possible to completely remove the
error in parallelism between the generating line of the
photosensitive drum and the axis of the pivot. Therefore, in this
embodiment, the elongated hole 21BY is formed so as to provide a
play of 0.5 mm-1.0 mm approx. to accommodate the variation in the
parts.
The direction of the elongated hole 21BY, as shown in FIG. 13, is
substantially the same as a direction 71 of the tangent line of an
arcuation 70 having a center at the position of contact between the
black developing device 21B (gap roller 21S) and the photosensitive
drum 15 and passing through the pivot of the black developing
device 21B.
In other words, the distance R (radius, or length of the arm) (FIG.
13) from the contact point between the black developing device 21B
and the photosensitive drum 15 to an any portion of the elongated
hole 21BY is constant. By this direction of the elongated hole
21BY, the parallelism deviation between the generating line of the
developing roller 21BS and the generating line of the
photosensitive drum 15 can be minimized, even if the swing shaft 54
is deviated toward one side of the elongated hole.
(Setting of the black developing device at the developing
position)
As described in the foregoing, when the user rotates the rotation
lever 51 in the clockwise direction with the black developing
device inserted and positioned, the black developing device 21B and
the swingable guide 50A swing integrally downwardly. At this time,
gap rollers 21S (FIG. 11) provided at the opposite ends of the
developing roller 21BS are contacted to photosensitive drum 15.
The gap rollers 21S have diameters slightly larger than that of the
developing roller 21BS, and therefore, a small gap or play is
provided between the developing roller 21BS and the photosensitive
drum 15.
The black developing device 21B, as shown in FIG. 7, is provided
exposed at a side surface of the rear side holder 21BR with
contacts 21BU1, 21BU2 for applying a bias voltage from the main
assembly 80 and for detecting the toner remaining amount. The
contact 21BU1 is a developing bias contact. The developing bias
contact 21BU1 is contacted to a main assembly developing bias
contact pin 62a (FIG. 14) which will be described hereinafter,
which is provided in the main assembly 80, when the black
developing device 21B is mounted to the main assembly 80. It
receives the developing bias to be applied to the developing roller
21BS from the main assembly 80. The contact 21BU2 is a remaining
amount detecting contact. When the black developing device 21B is
mounted to the main assembly 80, and the developing bias is applied
to the developing roller 21BS through the developing bias contact
21BU1, the remaining amount detecting contact 21BU2 transmits an
electric signal to be supplied to a detecting means (unshown)
provided in the main assembly 80. The value of the electric signal
is discriminated by the detecting means (unshown) through the main
assembly toner remaining amount detecting pin 62b (FIG. 14) which
will be described hereinafter, so that main assembly 80 can detect
that toner remaining amount in the toner accommodating portion 21BK
is smaller than a predetermined amount. When the main assembly 80
detects that toner remaining amount in the toner accommodating
portion 21BK is smaller than a first predetermined amount, the main
assembly 80 notifies the user of the necessity of exchange of the
black developing device 21B (for example, flickering of a lamp)
(level 1). Thereafter, when the main assembly 80 detects that toner
remaining amount in the toner accommodating portion 21BK is smaller
than a second predetermined amount, the main assembly 80 of the
apparatus is stopped (level 2).
The electric signal is produced in accordance with the
electrostatic capacity between a developing roller 21BS and an
antenna (unshown).
On the other hand, the main assembly contact pins 62a, 62b are
provided at the rear side of the main assembly 80. The contacts
21BU1, 21BU2 of the black developing device 21B and the main
assembly contact pins 62a, 62b are contacted to each other, so that
electrical connection is established therebetween.
As shown in FIGS. 12 and 13, the orientation of the rotation lever
51 is vertical, and caps a part of the insertion opening 63 for the
black developing device. Therefore, even if the user attempts to
pull the black developing device 21B out, it abuts the rotation
lever 51 and is not taken out.
Accordingly, when the user pulls the black developing device 21B
out of the main assembly, the rotation lever 51 has to be rotated
to a horizontal position. Only in such a state, the black
developing device 21B can be mounted to or demounted from the main
assembly.
(Removal of the black developing device)
When the black developing device 21B is to be removed from the main
assembly 80 of the apparatus, the rotation lever 51 is rotated to a
horizontal position (FIG. 3). By pulling the black developing
device 21B, it can be removed out. In this embodiment, the front
side holder 21BF of the black developing device 21B is provided
with an integrally formed grip portion 21BX which can be hooked by
fingers, as shown in FIG. 12. Therefore, the user can smoothly
pulls the black developing device 21B out using the grip portion
21BX.
Immediately before the black developing device 21B is pulled out of
the main assembly 80, the elongated hole 21BY formed in the front
side holder 21BF is engaged with the swing shaft 54. That is, the
black developing device 21B is supported by the swing shaft 54 at
the front side. Therefore, when the elongated hole 21BY is
disengaged from the swing shaft 54, the black developing device 21B
lowers by the weight thereof, so that black developing device 21B
is supported by the swingable guide 50A.
In this embodiment, the engagement length between the swing shaft
54 and the elongated hole 21BY is long enough. More particularly,
as shown in FIG. 9, when the black developing device 21B is
mounted, and the is disposed at the rear side beyond the end
surface B of the opening of the insertion opening 63, the
engagement length L between the swing shaft 54 (supporting portion
of the main assembly 80) and the elongated hole 21BY (front side
pivot of the developing device 21B) is longer than the distance L1
between the wall surface C of the developing device 21B which is
closest to the end surface B of the opening and the end surface B
of the opening. By doing so, when the elongated hole 21BY is
disengaged from the swing shaft 54, the wall surface C of the black
developing device is prevented from abutting the member defining
the opening of the insertion opening 63.
Referring to FIGS. 16, 17 and 18, other embodiments will be
described.
FIG. 16 is a side view of a leading side of the black developing
device with respect to the mounting direction of the black
developing device (mounted in the main assembly); FIG. 17 is a side
view of a trailing side of the black developing device (mounted in
the main assembly); and FIG. 18 is a side view of the black
developing device located at the developing position.
In this embodiment, the angle of the longitudinal direction of the
elongated hole 21BY (line L2) is within approx.
5.degree.-15.degree. relative to the line L3 connecting the center
of the female coupling recess 21B9 and the center of the hole 21BD.
Preferably, the above-described angle is 5.degree. approx.
According to this embodiment, when the black developing cartridge
21B is mounted to the development position of the main assembly 80,
the longitudinal direction (direction indicated by the arrow L2 in
FIG. 18) of the elongated hole 21BY is substantially codirectional
with the direction in which the developing roller 21BS is urged
toward the peripheral surface of the photosensitive drum 15
(direction indicated by the arrow L4 in FIG. 18) (as shown in FIG.
18, lines L2, L4 are substantially parallel).
Therefore, even if there is an assembling error in the image
forming apparatus P, an error in the parts thereof, an assembling
error in the black developing cartridge 21B or an error in the part
thereof, the black developing cartridge 21B is correctly positioned
to the developing position within the range of the elongated hole
21BY, since the developing roller 21BS is movable toward and away
from the peripheral surface of the photosensitive drum 15
(directions indicated by the arrow Y in FIG. 18).
In FIG. 18, designated by 73 is a portion where a grip (unshown)
for pulling the toner seal (unshown) has been provided.
The positioning of the black developing cartridge 21B in the
foregoing embodiment is summarized as follows:
1. The developing cartridge (21B) for developing a latent image
formed on a photosensitive member (15), which is detachably
mountable relative to a main assembly (80) of an
electrophotographic image forming apparatus, comprises:
a developing member (e.g. 21BS) for developing a latent image
formed on the photosensitive member;
a toner accommodating portion (e.g. 21BK) for accommodating toner
to be used for developing the latent image formed on the
photosensitive member by said developing member;
a first recess (e.g. 21BD) for engagement with a first positioning
member provided in the main assembly, said first recess being
provided at a leading side end portion (holder 21BR side) of said
developing cartridge when it is mounted to the main assembly in a
longitudinal direction of said developing member;
a second recess (e.g. 21BR1) for engagement with a second
positioning member provided in the main assembly, said second
recess being provided at the leading side end portion of said
developing cartridge when it is mounted to the main assembly in the
longitudinal direction of said developing member;
a driving force receiving member (21BG), provided in said second
recess, for receiving driving force for rotating said developing
member from the main assembly;
a third recess (21BY) for engagement with a third positioning
member provided in the main assembly, said third recess being
provided at a trailing side end portion (e.g. holder 21BF side) of
said developing cartridge when it is mounted to the main assembly
in the longitudinal direction of said developing member, wherein
said third recess is provided in a free end portion of an arm (e.g.
21BF1) projected in a direction crossing with the longitudinal
direction of said developing member.
2. Said first recess (e.g. 21BD) has an elongated hole
configuration.
3. Said second recess (21BR1) has a circular configuration.
4. Said third recess (21BY) has an elongated hole
configuration.
5. An angle between a longitudinal direction of the elongated hole
configuration of said third recess (e.g. 21BY) and a line
connecting centers of said first recess (e.g. 21BD) and said second
recess (e.g. 21BR1) is approx. 5.0.degree.-15.0.degree..
6. The cartridge further comprises a first guide portion (e.g.
21BC1) and a second guide portion (e.g. 21BC2), extended in the
longitudinal direction of said developing member, for guiding said
developing cartridge when said developing cartridge is mounted to
the main assembly in the longitudinal direction of said developing
member.
7. The longitudinal direction of the elongated hole configuration
of said first recess (21BD) is directed substantially toward said
second recess (e.g. 21BR1).
8. A diameter of said second recess (e.g. 21BR1) is larger than a
length, measured in the longitudinal direction of the elongated
hole configuration, of said first recess (21BD).
9. The length of said first recess (e.g. 21BD) is not less than
approx. 9.0 mm, and a width thereof is approx. 7.0 mm-9.0 mm, and a
diameter of said second recess (e.g. 21BR1) is approx. 8.0 mm-10.0
mm.
10. The length of said third recess (e.g. 21BY) is approx. 8.0
mm-10.0 mm, and the width thereof is approx. 7.0 mm-9.0 mm.
11. The main assembly (e.g. 80) includes a swingable supporting
member (e.g. 50) for supporting said developing cartridge (e.g.
21B), said swingable supporting member being swingable about an
axis (e.g. 54, 55) between a developing position for placing said
developing cartridge at an operating position and a retracted
position retracted from the operating position, wherein said first
positioning member (e.g. 50K) and said second positioning member
(e.g. 50L) are provided on said swingable supporting member at a
rear side of said swingable supporting member, and wherein said
third positioning member (e.g. 54) is disposed on an extension of
the axis.
12. Said first recess (e.g. 21BD) is disposed adjacent one
longitudinal end of said developing member in a direction crossing
with the longitudinal direction of said developing member, and said
second recess (21BR1) is disposed at one longitudinal end of said
toner accommodating portion (e.g. 21BK).
13. The developing cartridge further comprises an exposed
developing bias contact (e.g. 21BU1), at said one end of said
developing cartridge, for receiving, from the main assembly, a
developing bias voltage to be supplied to said developing member
when said developing cartridge is mounted to the main assembly.
14. The developing cartridge further comprises an exposed toner
remaining amount detecting contact (e.g. 21BU2), at said one end of
said developing cartridge, for permitting the main assembly to
detects a toner remaining amount in said toner accommodating
portion, said remaining amount detecting contact being juxtaposed
with said developing bias contact (e.g. 21BU1).
15. The developing cartridge further comprises a shutter (e.g.
21BO) movable between a covering position for covering a surface of
said developing member and an exposing position, retracted from
said covering position, for exposing a surface of said developing
member, and wherein a first center (e.g. 21BP2) of rotation of a
first supporting arm (e.g. 21BP) for supporting one longitudinal
end of said shutter and a second center (e.g. 21BQ1) of rotation of
second supporting arm (e.g. 21BQ) for supporting the other
longitudinal end of said shutter are provided at said one
longitudinal end of said developing cartridge.
The drive transmission for the black developing cartridge 21B in
the foregoing embodiment is summarized as follows:
1. A developing cartridge (e.g. 21B) for developing a latent image
formed on the photosensitive member (e.g. 15), which is detachably
mountable to a main assembly (e.g. 80) of an electrophotographic
image forming apparatus, comprises:
a developing member (e.g. 21BS) for developing a latent image
formed on the photosensitive member;
a toner accommodating portion (e.g. 21BK) for accommodating toner
to be used for developing a latent image formed on said
photosensitive member by said developing member;
a driving force receiving portion (e.g. 21BG) for receiving, from
the main assembly, driving force for rotating said developing
member when said developing cartridge is mounted to the main
assembly, said driving force receiving portion being provided at a
leading side (e.g. 21BR side) of said developing cartridge when
said developing cartridge is mounted to the main assembly in a
longitudinal direction of said developing member;
an exposed developing bias contact (e.g. 21BU1), provided at said
leading side, for receiving from the main assembly a developing
bias to be supplied to said developing member when said developing
cartridge is mounted to the main assembly;
wherein said driving force receiving portion is disposed inside
said developing bias contact in the longitudinal direction of the
developing member. Since the driving force receiving member is
disposed in the recess, it is not easily damaged, so that the
rotational accuracy can be maintained.
2. Said driving force receiving portion (e.g. 21BG) is disposed in
a hole (e.g. 21BR1) provided in said cartridge frame, and said hole
is engaged with a positioning member (e.g. 50L) provided in the
main assembly when said developing cartridge is mounted to the main
assembly.
3. Said driving force receiving portion is in the form of a
circular member (e.g. 21BG) having an axis at a position different
from that of an axis of a developing roller (e.g. 21BS) as said
developing member, wherein said circular member is engaged with a
driving force transmission member (e.g. 50E) provided in the main
assembly with axial movement thereof, and by rotation of said
driving force transmission member, said circular member is
rotated.
4. The driving force received by said circular member (e.g. 21BG)
is transmitted to one end of said developing roller (e.g. 21BS)
through a gear (e.g. 50F) disposed coaxial with said developing
roller.
5. The cartridge further comprises an exposed toner remaining
amount detecting contact (e.g. 21BU2), juxtaposed adjacent said
developing bias contact (e.g. 21BU1), for permitting the main
assembly to detects a remaining amount of toner in said toner
accommodating portion.
6. A free end side of said driving force receiving portion (e.g.
21BG) is disposed inside a surface of said developing bias contact
(e.g. 21BU1) by approx. 8.0 mm-18.0 mm. By this, when the black
developing device is mounted by moving it in its longitudinal
direction, the driving force receiving member 21BG and the driving
force transmitting member 50E can be engaged after the cartridge is
correctly positioned by the positioning member 50L. Additionally,
after the positioning, the electric contacts 21BU1 and 21BU2 can be
contacted to the main assembly pins 62a and 62b.
7. The cartridge further comprises a shutter (e.g. 21BO) movable
between a covering position for covering a surface of said
developing member and an exposing position, retracted from said
covering position, for exposing a surface of said developing
member, wherein a first center of rotation of a first supporting
arm (e.g. 21BP) for supporting one longitudinal end of said shutter
and a second center of rotation of second supporting arm (e.g.
21BQ1) for supporting the other longitudinal end of said shutter,
are provided at said one longitudinal end of said developing
cartridge.
8. The cartridge further comprises a grip (e.g. 21BX) at the other
end of said developing cartridge, which is usable when said
developing cartridge is mounted to or demounted from the main
assembly.
9. The cartridge further comprises a second grip, at the other end
of said developing cartridge, for pulling out a toner seal 21B7
(FIG. 11) for unsealably sealing a toner supply opening (e.g.
21BK1) of said toner accommodating portion, and wherein by pulling
out the toner seal 21BT (FIG. 11) using said second grip before
start of use of said cartridge, said toner supply opening 21BK1 is
opened to permit the toner to be supplied to said developing member
from said toner accommodating portion.
The foregoing embodiments are directed to a color image forming
apparatus as an example, but the present invention is applicable to
a monochromatic image forming apparatus. In the foregoing
embodiments, the black development cartridge is taken as an
example, the present invention is applicable to a color development
cartridge.
In the foregoing embodiments, the printer is taken as an example,
but the present invention is applicable to a copying machine,
facsimile machine or another electrophotographic recording system
image forming apparatus.
According to the present invention, the developing device can be
properly mounted or demounted by inserting or pulling it along the
swingable guide portion of the image forming apparatus. Therefore,
in a color image forming apparatus, the black developing device
which can accommodate a large amount of toner can be easily mounted
or demounted.
With the swing axis of the swingable guide portion parallel with
the generating line of the electrophotographic photosensitive
member, the parallelism between the developing roller of the
developing device and the electrophotographic photosensitive member
is easily assured so that developing device and the main assembly
of the image forming apparatus can be correctly positioned, and
therefore, high quality images can be produced.
As described in the foregoing, according to the present invention,
the positioning of the developing cartridge relative to the main
assembly of the electrophotographic image forming apparatus can be
improved.
While the invention has been described with reference to the
structures disclosed herein, it is not confined to the details set
forth and this application is intended to cover such modifications
or changes as may come within the purposes of the improvements or
the scope of the following claims.
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